Detecting over programmed memory
AssigneeSanDisk Corporation
InventorsJian Chen, Yan Li, Jeffrey W. Lutze
Life of this patent
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Abstract
In a non-volatile semiconductor memory system (or other type of memory system), a memory cell is programmed by changing the threshold voltage of that memory cell. Because of variations in the programming speeds of different memory cells in the system, the possibility exists that some memory cells will be over programmed. That is, in one example, the threshold voltage will be moved past the intended value or range of values. The present invention includes determining whether the memory cells are over programmed.
Claims30
A method for detecting over programming in a memory system that uses multiple logical pages, comprising the steps of:
- programming a first multi-state storage element with data for a particular logical page;
- and
- using data from a logical page different than said particular logical page to determine whether said step of programming said first multi-state storage element over programmed said multi-state storage element.
A method for detecting over programming in a memory system that uses multiple logical pages, comprising the steps of:
- determining whether a threshold voltage of a first multi-state storage element is greater than a compare value, said first multi-state storage element stores information for at least a first logical page and a second logical page, said step of determining whether said threshold voltage of said first multi-state storage element is greater than said compare value is performed after writing data to said second logical page;
- and
- determining whether said first multi-state storage element is over programmed based on data from said first logical page and said step of determining whether a threshold voltage of a first multi-state storage element is greater than a compare value.
A memory system, comprising:
- an array of storage elements;
- and
- a managing circuit in communication with said array of storage elements, said managing circuit performs programming operations including programming a first multi-state storage element with data for a particular logical page, said managing circuit also performs over programming detection including using data from a logical page different than said particular logical page to determine whether said programming of said first multi-state storage element with data for said particular logical page over programmed said first multi-state storage element.
A memory system using multiple logical pages, comprising:
- means for programming a first multi-state storage element with data for a particular logical page;
- and
- means for using data from a logical page different than said particular logical page to determine whether said first multi-state storage element is over programmed.
Dependencies are inferred from the claim text.